Kalinin K-7 :: Nauka ~ Tehnika ~ Military

Kalinin K-7
1933
BOMBER, PASSENGER

Kalinin K-7



Designed by World War I aviator Konstantin Kalinin with a wingspan greater than a B-52's and a much greater wing area, the K-7 was one of the biggest aircraft built before the jet age. It was only one engine short of the B-52 as well, having the curious arrangement of six pulling on the wing leading edge and one pushing at the rear.

The K-7's very brief first flight showed up instability and serious vibration caused by the airframe resonating with the engine frequency. The solution to this 'flutter' was thought to be to shorten and strengthen the tail booms, little being known then about the natural frequencies of structures and their response to vibration. On the 11th flight, during a speed test, the port tailboom vibrated, fractured, jammed the elevator and caused the giant aircraft to plough into the ground, killing 15.

Undaunted by this disaster, Kalinin's team began construction of two further K-7s in a new factory, but the vicissitudes of Stalin's Russia saw the project abandoned, and in 1938 the arrest and execution of Kalinin on trumped up espionage and sabotage charges.

Jim Winchester "The World's Worst Aircraft", 2005

3-View
Kalinin K-7   A three-view drawing (800 x 964)

Specification
CREW   12
PASSENGERS   128
ENGINE   7 x M34F, 550kW
WEIGHTS
Take-off weight   38000 kg   83776 lb
Empty weight   24400 kg   53793 lb
DIMENSIONS
Wingspan   53.0 m   173 ft 11 in
Length   28.0 m   91 ft 10 in
Wing area   454.0 m2   4886.81 sq ft
PERFORMANCE
Max. speed   234 km/h   145 mph
Cruise speed   180 km/h   112 mph
Ceiling   4000 m   13100 ft
Range   3030 km   1883 miles